Apparatus for trapping dust arising



'Feb. 7, 1939.. J. N. HUNTER 20,998

APPARATUS FOR TRAPPING DUST ARISING IN'BORE HOLES Original Filed Jan. 8,19:56

ATTORNEYS v f3 INVENTOR.

Reissued Feb. 7, 1939 UNITED STATES APPARATUS FOR TRAPPING DUST ARISINGIN BORE HOLES John Norman Hunter, Norbury, England, assignor to PyreneManufacturing Comp-any, N. J., a corporation of Delaware Original No.2,107,864,

Serial No. 58,043, January 8, 1936.

Newark,

dated February I' 8, l 1938, Application for reissue June 14, 1938,Serial No. 213,656. In Great Britain February 6, 1935 3 Claims.

According to the invention a suction tube arranged to surround a drillshank is formed with a mouth which is adapted to enter the mouth of abore hole and which is preferably tapered for this purpose, and is alsoformed with a connection through which suction may be applied. Thus whenthe end of the suction tube has been lodged in the bore hole the tubeserves not only as a receiver for the dust but also as a guide for thedrill shank. The tube is preferably made of spring steel or equivalentresilient material and is slotted or slit at the mouth end so that thelatter can bear tightly against the wall of the bore hole.

Inorder to catch any dust that arises when drilling starts, a'hood maybe mounted on the suction tube and arranged to surround the end of thedrill when a drilling operation is being begun, that is to say before ahole of sufficient depth has been made to receive the mouth of thesuction tube.

In order that the invention may be clearly understood and readilycarried into effect two apparatus constructed in accordance therewithwill now be described by way of example with reference to theaccompanying drawing, in which the two figures respectively show theseapparatus partly in section.

Fig. 1 is an elevational view, partly in section, of one embodiment ofmy invention and Fig. 2 is a similar view of a modified form.

Referring first to Fig. 1, a suction tube or shell forming an outletchamber is arranged around the shank 2 of a drill, and at the mouth endis formed with a tapering portion or spout 3, the mouth-of which isnarrower than the bit 4 of the drill. The tapered portion is formed witha slot or opening 5 which runs helically around it. A branch or outletBis connected by a flexible pipe i to an ejector or other form ofsuction pipe which causes the dust to be drawn away from the bore holeduring the drilling. A flexible hood or skirt 8 surrounds thesuction'tube I and can be pushed either into the position shown in Fig.l or into a position in which the free end of the hood projects beyondthe bit 4. As a. rule when drilling begins the hood is pushed forward sothat its edge bears on the rock face and surrounds the area upon whichthe drill acts. However, if considerable suction is applied through thebranch pipe 6 it is found that the dust initially formed is drawn intothe annular chamber within the hood and through the slot 5 into theoutlet chamber, even if the hood is in the position shown in Fig. 1. Inpractice the operator supports the end of the drill shank by holding thesuction tube I in one hand, and as drilling proceeds the tube enters thehole. As soon as the hole has been made sumciently deep to support theend of the suction tube there is no longer any need for the operator tohold this tube.

As is clearly shown by Fig. l, the suction tube is made of such diameterthat the drill shank can revolve freely and does not obstruct the freeflow of dust up the tube and through the branch 6.

In the construction shown in Fig. 2, the mouth end of the spout 3 of thetube or shell 1 is formed with straight longitudinal slits or openings 9and is surrounded by a hood or skirt ID of a slightly different designfrom that shown in Fig. 1. In this case the flexible conical part of thehood is carried by a stiff annular member 14 which may be arranged toslide on the tube I.

If the suction exerted through the branch or outlet 6 is insufficient toinsure that all the dust is drawn through the branch 6, the end of thetube may be positively sealed, as shown in Fig. 2, to prevent any airescaping between the tube and the drill shank 2. This scaling iseffected by an annular rubber disc H which fits around the drill shank 2and is covered by a metal ring if at its rim. This rim l2 lies in agroove formed in a casting I3 fixed to the end of the tube i and floatsin this groove so that the whole seal also constitutes a bearing for thedrill shank 2.

It will be understood that the invention may assume forms other thanthose herein shown and described without departing from the spirit ofthe invention or the scope of the following claims.

What is claimed is:

1. An apparatus for trapping dust arising in bore holes, comprising atube of resilient metal adapted to surround a drill shank and providedwith a connection through which suction may be induced, the wall of saidtube being gradually tapered throughout a substantial portion of itslength to facilitate its partial entrance into a bore hole and slottedalso throughout a substantial portion of its length to render it readilycontractible under the impinging action exerted thereon by the wall ofthe bore hole as it enters the same, the slotted area of said wall beingsufiiciently long to serve as a passage through which air is drawn intothe tube from the vicinity of the outer end of the bore hole under theaction of induced suction within the tube during such time as thetapered end of the tube is partially disposed within the bore hole.

2. An apparatus for trapping dust arising in bore holes, comprising atube of resilient metal adapted to surround a drill shank and providedwith a connection through which suction may be induced, the wall of saidtube being gradually tapered throughout a substantial portion oi itslength to facilitate its entering a bore hole and slotted alsothroughout a substantial portion of its length to render it readilycontractible under the impinging action exerted thereon by the wall ofthe bore hole as it enters the same, the slotted 15 area of said wallextending along ahelicalpathand serving as a passage through which airis drawn into the tube from the vicinity of the outer end of the borehole under the action of induced suction within the tube during suchtime as the tapered end of the tube is disposed within the bore hole.

3. A drill hood including a shell closed at one end creating an. outletchamber, a spout smaller in diameter than said shell projecting from theopposite end of said shell and having openings into said outlet chamber,a skirt projecting from said shell and surrounding said spout creatingan. annular chamber communicating with said openings, and an outlet fromsaid outlet chamber.

JOHN NORMAN HUNTER.

